> You have a good point that aiming at 4kB makes 8kB a very safe choice.

Not really no - we use separate IRQ stacks in 4K but not 8K mode onx86-32. That means you've actually got no more space if you are unluckywith the timing of events. The 8K mode is merely harder to debug.

If 4K stacks really are not safe then x86-32 really really needs toswitch to using IRQ stacks in 8K stack mode as well.